Diffuser



R. D. TUTT June 19, 1956 DIFFUSER 2 Sheets-Shem 1 Filed Feb. 14, 195] 3 O Q j 3nventor 74 73 RICHARD D TUTT PERFO/FATED PLA r5 (Ittomegs R. D. TUTT June 19, 1956 D IFFUSER 2 Sheets-Sheet 2 Filed Feb. 14, 1951 3nventor RICHARD D TUTT u MM W (Ittornegs United States Patent DIFFUSER Richard D. Tutt, New Britain, Conm, assignor, by mesne assignments, to Allied Thermal Corporation, New Britain, Conn., a corporation of Connecticut Application February 14, 1951, Serial No. 210,838

13 Claims. (Cl. 9840) The present invention relates to air diffusers for use in air conditioning and distributing systems. In the preferred embodiment, the diffuser is utilized in a wall, preferably the ceiling, of an enclosure in connection with a supply of primary air under pressure and operates efficiently to mix the primary air with room air and to disperse the mixture of room and primary air into the room in an advantageous and satisfactory manner.

The diffuser of the present invention is particularly advantageous for use in systems where it is desired to supply the primary air at relatively high pressures, i. e., at pressures up to inches of water, or more. The diffuser is effective not only for inducing a flow of a desired quantity of room air for admixture with the primary air and a dispersal of the mixed air into the room in a stream having acceptable throw and drop characteristics but, in addition, is effective for avoiding an undesirable increase in the noise level of the enclosure which normally accompanics the use of high pressure air.

It is an object of the present invention to provide a diffuser having an intake for room air and means for controlling the release of primary air under elevated pressure in such fashion that the flow of primary air effectively induces a desired intake flow of room air for admixture with the primary air and so that the resulting mixture is dispersed into the room in a stream of satisfactory throw, temperature, and drop characteristics. 7

A further object is to provide a diffuser of the type referred to having novel and effective means within the diffuser for attenuating noise whereby the operation of the diffuser in connection with high pressure air is rendered satisfactory from a noise standpoint.

A further object of the present invention is to provide a diffuser of the character referred to having greatly improved operating characteristics, but which, at the same time, has a compactness and simplicity of construction rendering it easy and economical to fabricate and assemble as well as a streamlined and pleasing appearance, whereby it may be used efficiently and conveniently in a wide variety of installations without detracting from the appearance of the room.

Another object of the invention is to provide a diffuser of the character referred to which will have a minimum of parts, particularly moving parts or parts which would deteriorate in use, whereby the difiuser will operate efficiently over long periods of time without breakdown or requiring repair or replacement.

Other objects will be in part obvious, and in part pointed out more in detail hereinafter.

The invention accordingly consists in the features of construction, combination of elements and arrangement of parts which will be exemplified in the construction hereafter set forth and the scope of the application of which will be indicated in the appended claims.

In the drawings:

Fig; 1 is a bottom view of a specific embodiment of the diffuser of the present invention, the diffuser being mounted in a ceiling or other supporting structure;

2,750,865 Patented June 19, 1956 Fig. 2 is a cross sectional view taken along the line 22 of Fig. 1;

Fig. 3 is a cross sectional view taken along the line 33 of Fig. 2; and

Fig. 4 is a cross sectional view taken along the line 44 of Fig. 3.

Referring to the drawings, air is admitted to the diffuser of the present invention from any convenient source (not shown) such as by means of a standard air conduit employed in air conditioning and distributing systems. In accordance with the invention, it is preferred to employ suitable damping means, such as the damper 10, at the entranceway for the primary air, the damper 10 being connected at its outer end 11 to the source of primary air. Since it is contemplated that the diffuser of the present invention will be utilized with air under relatively high pressure, there has been illustrated a damper 10 of the type shown in the co-pending application of Nelson M. Payne, Serial No. 177,859, filed August 5, 1950, now Patent No. 2,713,350. In general, a damper of this type is provided with a generally tear-drop shaped housing 12 having an axial outlet opening 13 adapted to be opened and closed by a plug 14 which is manipulated by a depending rotatable adjusting rod 15 having a suitable manually operable knob 16 on the lower end thereof. When high pressure air is utilized, there is a tendency for a damper to introduce noise into the system, this being particularly noticed as a whistlelike sound as the size of the effective opening of the damper is decreased and, for this reason, it is preferred to utilize a damper of the construction referred to here which does not have this disadvantage.

The outlet opening 13 of the damper communicates with the upper end of a cylindrical chamber 20 which is defined by a cylindrical side wall 21 and a circular end wall 22. The damper 10 is preferably disposed generally radially of the chamber 20 so that the flow of primary air received through the damper 10 will be directed centrally of the chamber 20.

The side wall 21 and end wall 22 are preferably formed of suitable sound absorbing material. For example, one material which I have found to be entirely satisfactory for this purpose is a commercially available soft board formed of pressed asbestos fibers. By reason of the sound absorbing qualities of the Walls 21 and 22, a certain amount of the noise transmitted by the high pressure air will be absorbed at this point.

Immediately below the entrance of the primary air there I is disposed a transverse sound plate 30 which extends completely across the chamber 20 and which may be suitably anchored in place by insertion between the bottom end of the wall 21 and a ring 23 registering with and forming a continuation of the wall 21 and also formed of sound absorbing material.

' The sound plate 30 is designed and constructed in accordance with the invention to effectively aid in the attenuation of the sound carried by the primary air. For this purpose, the plate 30 is preferably formed of sheet metal, for example, of sheet steel, so as to have a high degree of rigidity. It is essential that the plate have a high degree of rigidity or stiffness so that it will not create a drum effect which would impart rather than attenuate sound in the system. I have found that sheet steel, in the range of 16 to 22 gauge, and preferably about 18 gauge, will generally form the most satisfactory sound plate for the present purposes.

Further, in accordance with the invention, the sound plate 30 is provided with a plurality of perforations. In the preferred form, the perforations are formed by striking out lip portions 33 defining restricted openings 31 of definite predetermined shape and size. It has been found that the openings defined by the lips 33 should be relatively small in size; otherwise, an undesirable amount of noise is admitted to pass through the plate 30. In general, it is believed that diameter of the openings preferably should not exceed 0.1 inch. For example, in one commercial embodiment of the invention, holes of approximately .07 inch in diameter have been found to provide desired results. It is important, moreover, that there shall be maintained a high ratio between closed and open areas of the plate. The best results appear to be obtained when the effective hole area does not exceed approximately 6 to 10 percent of the gross area of the plate. For convenience, there has been illustrated in Fig. 3 of the drawings a manner of spacing the perforations 31 so as to provide the desired high ratio of closed to open area. As viewed in Fig. 3, the openings 31 are disposed in a plurality of groups 32 and in the lines extending generally parallel to a line between the lower left-hand and upper right-hand corner and the perforations 31 are spaced fairly closely together, such as approximately nine thirtyseconds inch between centers. The perforations 31 falling in a line generally parallel to a line between the lower right-hand and upper left-hand corners are spaced slightly farther apart such as a distance of seven-sixteenths inch between centers. The perforations may be grouped, as shown, to increase the ratio of closed to open area.

Beneath the ring 23, but spaced therefrom, there is disposed a transverse annular or ring-shaped baffle plate 40 which is formed of a relatively thick sheet of sound absorbing material such as the soft pressed asbestos fiber board from which the walls 21, 22 and 23 are formed. By way of example, the central opening 41 of the baffie plate 40 may have a diameter which is of the order of onethird the diameter of the plate 40. The baflie 40 is spaced from the sound plate 30 by disposing it on the bottom edge of the ring 23. Beneath the baffle 40, the cylindrical chamber is continued by a cylindrical wall 24 and the bottom thereof is partially closed by an annular ring-like bottom wall 25. Here again, the preferred material utilized in forming the walls 24 and 25 is a sound absorbing material.

Situated beneath the opening 41 of the baflie 40 and intermediate the baffle and the bottom wall 25 is a circular or disk-like baffle 42 also formed of sound absorbing material. The disk-like baflie 42 may be supported in any convenient manner such as by means of a plurality of sleeves 43 received on studs 44 extending between the baflie 40 and the bottom wall 25. The diameter of the baffle 42 is preferably of the order of three-fourths the diameter of the chamber.

A central circular opening 26 in the bottom wall 25 is provided for the release of the air into the venturi and diffusing section of the diffuser, to be described immediately hereafter. The opening 26 is of smaller diameter than the bafile 42.

Accordingly, it will be seen that, when primary air is admitted into the chamber 20 through the damper 10, the flow of air is first expanded outwardly and given a uniform vertical direction by passage through the sound plate 30. At the same time some of the sound carried by the primary air is absorbed by the walls 21 and 22. Some of the sound will be reflected by the sound plate 30 so as to increase the absorption thereof by the Walls 21 and 22. Some of the sound also will cause vibration of the plate 30, thus absorbing energy of the sound. The air which has passed through the perforations 31 in the plate 30 is then forced to strike against the baffle plates and 42, since these plates, in connection with the side walls, form a tortuous passage for the air. The resulting impact of the sound waves at right angles to the baffles 40 and 42 results in a very eflicient and high degree of sound attenuation.

As a result of the structure just described, the primary air is conditioned for release into the room without raising the noise level of the room beyond acceptable limits. It is an advantage of the present invention that this efficient sound absorption may be carried out in a unit which is as small as two feet in diameter and less than a foot in height, between the upper wall 22 and bottom wall 25.

Turning now to the venturi and air dispersing section of the difiuser, as best shown in Figs. 1 and 2 of the drawings, there is provided an outer or peripheral vane which is generally frusto-conical in shape and which is provided with a circular flange 51 at its upper end for registry with the periphery of the opening 26. The lower extremity of the vane 50 is in the form of a horizontal flange 52 of generally square configuration, the merging surfaces being rounded off to give a smooth uninterrupted surface. The flange 52 is adapted to rest against the under surface of the ceiling or other supporting structure shown generally at 53.

Within the confines of the upper circular flange 51, there is positioned a disk 54 of lesser diameter than opening 26 and having a downwardly bent peripheral portion 55 defining an annular air passageway therebetween. The disk 54, which may be formed of sheet metal, may be supported in the position shown by means of a plurality of posts 56 secured to the baflle 42.

In accordance with the invention, the flange 51 is engaged by a ring-like member 60 having an outwardly flared arcuate end portion 61. There also is secured to the rim 55 of disk 54 a generally frusto-conical plate 62 which is co-extensive with member 60. The result is that the plates 60 and 62 define an annular diagonally, i. e. outwardly and downwardly, directed venturi opening 63 spaced adjacent the inner surface of the peripheral vane 50.

Disposed beneath the disk 54 and generally within the deflector 50 are nested rings and 71 which are coaxially positioned as shown in the drawings at respectively lower levels by any suitable supporting means (not shown). The rings 70 and 71 are generally frusto-conical and are open at the top and bottom. The bottom edges are bent outwardly in the form of horizontal flanges 73 and 74, respectively, which are generally similar in shape to the flange 52 of the peripheral vane 50, i. e., generally square in configuration, with the intermediate area smoothly rounded out to permit a transition from circular to square form. A center baflle 72 which is closed at the top by a rectangular section 75 and provided with a rectangular flange 76 is axially supported by any suitable means not shown).

In the operation of the device, the primary air from which the sound has been effectively attenuated is released through the annular venturi opening 63. This induces a flow of room air upwardly through the diagonal entranceways provided by the spaces between the rings 70, 71 and 72. The air drawn upwardly from the room through these passageways is then mixed with the primary air issuing from the venturi opening 63 and the mixture is dispersed outwardly through the passageway between the ring 70 and the outer vane 50. The arrangement is such that a stream of air is produced which is generally parallel to but spaced from the supporting surface 52 and the flow is substantially uniform in all directions radially of the central axis of the diffuser to form a circular pattern. This has been found to be a distinct advantage of the diffuser of the present invention in that I have found that, when the square face of the diffuser is mounted flush with the ceiling and the diffused air forms a circular air pattern similar to that emanating from a round diffuser, smudging is practically avoided. It thus will be seen that, when the deflector is installed in an enclosure, an upward flow of room air is drawn into the diffuser centrally thereof and the mixture of room air and primary air is dispersed outwardly along the ceiling from which it eventually drops and joins the returning flow of room air. It is an advantage of the arrangement of the diffuser of the present invention that a high ratio of room air to primary air is induced. A one-to-one or greater ratio can easily be obtained. As.

'5 a result, the pressure and temperature differential of the primary air may be increased without adversely affecting the throw and drop characteristics of the stream of mixed room and primary air being dispersed from the difiuser.

The arrangement of the diffuser in accordance with the invention is such that a highly compact and efficient sound attenuating and air diffusing unit is produced which is highly eflicient and thus permits the use of high pressure air without undesirably increasing the noise level of the enclosure and produces a desired mixture of primary air with room air having among its many advantages the dispersing of a stream of air into the enclosure having desirable throw and drop characteristics. Furthermore, the diffusing section is of simple design rendering it economical to produce and is arranged in a desirable square or rectangular configuration rendering the dilfuser more adaptable for use in modern designs of enclosures and also giving a desired directional compo nent to the stream of air dispersed through the diffuser.

As many changes could be made in the above construction and many apparently widely difierent embodiments of this invention could be made without departing from the scope thereof, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

It is also to be understood that the language used in the following claims is intended to cover all of the generic and specific features of the invention herein described and all statements of the scope of the invention which, as a matter of language, might be said to fall therebetween.

I claim as my invention:

1. In a diffuser, a generally frusto-conical vane having a generally rectangular outwardly directed flange at its lower end, an annular outwardly and downwardly directed venturi nozzle adjacent the inner surface of the vane, and a second generally frusto-conical vane of smaller diameter than the first vane and of similar shape disposed generally coaxially with the first vane to form an interior air inlet passageway to the space adjacent the venturi nozzle and an air outlet passageway of substantially constant width between the vanes, said second vane having a generally rectangular outwardly extending flange of smaller size than the flange of the first vane and disposed at a greater distance from the nozzle.

2. In a diffuser, a generally frusto-conical vane having a generally rectangular outwardly directed flange at its lower end, an annular outwardly and downwardly directed venturi nozzle disposed adjacent the inner surface of the vane, a plurality of concentric and spaced apart generally frusto-conical rings within the vane forming interior air inlet passageways to the space adjacent the venturi nozzle and an air outlet passageway between the outer ring and the vane, said rings being provided with generally rectangular outwardly extending flanges of progressively smaller size and disposed at progressively greater distances from the venturi nozzle than the flange of the vane.

3. In a diffuser, a generally frusto-conical outer vane having a generally rectangular outwardly directed flange at its lower end, an annular outwardly and downwardly directed venturi nozzle disposed adjacent the inner surface of the vane, a plurality of concentric and spaced apart generally frusto-conical rings within the vane forming an interior air inlet to the space adjacent the venturi nozzle and an air outlet passageway between the outer ring and the vane, said rings being provided with generally rectangular outwardly extending flanges of progressively smaller size and disposed at progressively greater distances from the nozzle than the flange of the outer vane, and the center ring having means closing the upper end thereof.

4. In a diffuser, a venturi nozzle, a plurality of vanes forming air inlet and outlet passageways adjacent the nozzle and means for connecting the nozzle to a source of air under pressure comprising a chamber having an interior surface of sound absorbing material and a sound attenuating member comprising a perforated plate extending across the chamber transversely to the flow of all.

5. In a diifuser, a venturi nozzle, a plurality of vanes forming air inlet and outlet passageways adjacent the nozzle, and means for connecting the nozzle to a source of air under pressure comprising a generally cylindrical chamber having an interior surface of sound absorbing material and a rigid metal plate extending across the chamber transversely to the flow of air having perforations in a minor proportion of its area.

6. In a diffuser, a sound absorbing and attenuating member for connection between a source of air under pressure and the air outlet of the difiuser comprising a generally cylindrical chamber having an interior surface formed of sound absorbing material, a relatively thin but rigid perforated metal plate extending transversely to the flow of air across the chamber intermediate the ends of the chamber and having both faces spaced from the sound-absorbing material, said plate being provided with a high ratio of imperforate to perforate area, a series of baffles of sound absorbing material in the lower end of the chamber, and a venturi type outlet disposed beneath the baffles.

7. In a diffuser, a sound absorbing and attenuating member for connection between a source of air under pressure and the air outlet of the diffuser comprising a generally cylindrical chamber having an interior surface formed of sound absorbing material, a relatively thin but rigid perforated plate extending across the chamber transversely to the flow of air and intermediate the ends of the chamber, a first baflle formed of sound absorbing material disposed below but spaced from the plate comprising an annular ring having a central air passageway, a second baflle formed of sound absorbing material disposed below but spaced from the first baffle comprising a disk of greater area than the central passageway of the first bafile, and means forming an air outlet disposed beneath the second baflle.

8. In a diffuser, a generally cylindrical chamber having an interior surface formed of sound absorbing material, an air inlet adjacent the upper end of the chamber, a sound attenuating member comprising a metal plate extending across the chamber intermediate its upper and lower ends and disposed transversely to the flow of air through the chamber, said plate having a plurality of nozzles extending axially of the chamber and spaced from the sound-absorbing material to form small open passageways through a minor proportion of the plate, and an annular venturi nozzle communicating with the lower end of the chamber.

9. In a diffuser, a generally cylindrical chamber having an interior surface formed of sound absorbing material, an inlet for primary air under pressure adjacent the upper end of the chamber, a perforated rigid metal plate extending across the chamber intermediate its ends transversely to the flow of air through the chamber, a first batfle formed of sound absorbing material disposed below but spaced from the plate comprising an annular ring having a central air passageway, a second baflle of sound absorbing material disposed below but spaced from the first baifle comprising a disk of greater area than the central passageway of the first baflle, and an annular venturi outlet nozzle disposed beneath the second baflle.

10. In a diffuser, a generally cylindrical chamber having an interior surface formed of sound absorbing material, an inlet for primary air under pressure adjacent the upper end of the chamber, a single rigid perforated metal plate extending across the chamber intermediate its ends and transversely to the flow of air through the chamber,

the perforations of said plate being of small size and comprising a minor proportion of the plate area, aseries of baffles formed of sound absorbing material extending transversely of the chamber and forming a tortuous air passageway through the remainder of the chamber, and an annular venturi outlet nozzle forming an air outlet from the bottom of the chamber.

11. A diffuser comprising a generally cylindrical chamber having an interior surface formed of sound absorbing material, an inlet for primary air adjacent the top of the chamber, a rigid perforated metal plate extending across the chamber intermediate its ends and transversely of the flow of air through the chamber, the perforations of said plate being of small size and comprising a minor proportion of the plate area, a series of bafi les formed of sound absorbing material extending transversely of the chamber defining a tortuous air passageway through the lower portion of the chamber, means forming an annular outwardly and downwardly directed venturi nozzle depending from and communicating with the bottom of the chamber, a first generally frusto-conical outer vane secured at its upper edge to the chamber and spaced radially outwardly from' the venturi nozzle, and a second generally frusto-conical inner vane of smaller diameter than the first vane and spaced radially inwardly of the venturi nozzle.

12. A diffuser comprising a generally cylindrical chamber having an interior surface formed of sound absorbing material, an inlet for primary air adjacent the top of the chamber, a rigid perforated metal plate extending across the chamber intermediate its ends and transversely of the flow of air through the chamber, the perforations of said plate being of small size and comprising a minor proportion of the plate area, a series of batfies formed of sound absorbing material extending transversely of the chamber defining a tortuous air passageway through the lower portion of the chamber, means forming an annular outwardly and downwardly directed venturi nozzle depending from and communicating with the bottom of the chamber, a first generally frusto-conical outer vane secured at its upper edge to the chamber and spaced radially outwardly from the venturi nozzle, and a plurality of concentric and spaced-apart frusto-conical rings Within the vane forming interior air inlet passageways to adjacent the venturi nozzle and an air outlet passageway between the outer of said rings and the vane registering with the venturi nozzle.

' 13. In a diffuser, a generally frusto-conical vane for insertion in a Wall orifice having a peripheral flange at its large end for engaging the wall surface, a plurality of concentric and spaced apart frusto-conical rings of similar shape and of progressively smaller diameter disposed within the vane to form a plurality of air passageways therebetween of substantially equal Width through out, the inner ring being closed at its smaller end and the large ends of the rings being formed with outwardly turned flanges of relatively narrow width, an annular venturi nozzle having a small cross section relative to the width of said passageways disposed between the vane and the next adjacent ring and extending into the passageway, the axis of said venturi nozzle being substantially parallel to that of the air passageway formed by said vane and the ring next adjacent thereto, and means for connecting the nozzle to a source of air under pressure.

References Cited in the file of this patent UNITED STATES PATENTS 1,006,595 Red Oct. 24, 1911 1,045,419 Matula Nov. 26, 1912 1,207,239 Templin Dec. 5, 1916 1,522,111 Franck-Philipson Jan 6, 1925 1,705,778 Munroe et a1. Mar. 19, 1929 2,009,343 Peik July 23, 1935 2,144,035 Smith Jan. 17, 1939 2,144,631 Kurth Jan. 24, 1939 2,166,838 Anderson July 18, 1939 2,199,525 Kurth May 7, 1940 2,616,355 McCabe et al. Nov. 4, 1952 2,644,389 Dauphinee 'July 7, 1953 FOREIGN PATENTS 457,798 Canada July 5, 1949 716,977 France Oct. 13, 1931 

